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P0300

P0300 on a 2017 Jeep Renegade

P0300 is a generic OBD2 powertrain code for random or multiple cylinder misfire. Unlike P0301 through P0308, it does not point to one specific cylinder, so the cause can be ignition, fuel, air, sensor, or mechanical.

Not your vehicle? See general P0300 info.

Most common causes on the 2017 Jeep Renegade

Ranked from 560 NHTSA owner complaints filed for this vehicle.

Sort by:
  1. 1

    Piston, rod, or bearing failure causing catastrophic loss of compression

    High severity

    This 1.4L turbo engine has a well-documented reliability problem: owners in this batch report a rod through the block, a cracked piston with zero cylinder-1 compression, an outright 'engine blew up' replacement, oil starvation, and low-oil-pressure stalling, all leading to misfire/no-run conditions and full engine replacement.

    Reported in 6 NHTSA complaints
  2. 2

    Cracked or broken intake/vacuum air lines

    Medium severity

    Owners describe the plastic air lines off the air filter housing as a known, common failure point on the first-generation 1.4L turbo that cracks or breaks during routine service, opening a vacuum leak that leans the mixture and can misfire.

    Reported in 1 NHTSA complaint
  3. 3

    Head gasket failure allowing coolant into a cylinder

    High severity

    One owner's engine wouldn't restart and was diagnosed with coolant intrusion into a cylinder, a classic misfire-then-no-start failure mode.

    Reported in 1 NHTSA complaint
    Parts:head gasket
  4. 4

    Severe ignition misfire (spark plugs or coils)

    Medium severity

    One owner reported severe multi-cylinder misfires accompanied by jerking and jolting under load, the textbook symptom of failing plugs or coil packs.

    Reported in 1 NHTSA complaint
    Parts:spark plugsignition coil
  5. 5

    Loss of fuel pressure from a failing pump assembly

    Medium severity

    One owner describes cracks in the oil pump housing alongside a loss of fuel pressure, which starves the engine of fuel and can trigger a lean misfire.

    Reported in 1 NHTSA complaint
    Parts:fuel pump
  6. 6

    Excessive oil consumption from worn piston rings

    High severity

    One owner's Renegade stalled while consuming an excessive amount of engine oil, consistent with worn rings dropping compression enough to misfire.

    Reported in 1 NHTSA complaint
  7. 7

    Clogged or leaking fuel injector

    Medium severity

    A fouled or leaking injector disrupts the spray pattern to one cylinder, causing a repeatable misfire on that cylinder.

    Common cause
    Parts:fuel injector
  8. 8

    Carbon-fouled intake valves

    Low severity

    Carbon buildup on the intake valves (common on direct-injection turbo engines) disrupts airflow and combustion until cleaned.

    Common cause

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0300 on your car still needs shop confirmation before any repair.

Common symptoms

  • Flashing or steady check engine light
  • Rough idle
  • Shaking under acceleration
  • Loss of power
  • Fuel smell from exhaust

What to check before replacing parts

1

Scan for cylinder-specific misfire codes

Look for: A companion P0301–P0308 pins the misfire to one cylinder — start there. P0300 with no cylinder code points at something hitting several at once: fuel pressure, a large vacuum leak, or timing.

2

Inspect the spark plugs and coils

Look for: Pull the plugs: black/sooty = rich, oily = oil intrusion, white/blistered = lean or overheating, cracked porcelain or an out-of-spec gap = replace. Then swap a coil to another cylinder — if a cylinder-specific code follows the coil, the coil is bad.

3

Check fuel trims for a vacuum leak

Look for: High positive short- and long-term trims (worst at idle, improving as RPM rises) mean unmetered air is getting in. Smoke-test the intake and listen for hissing.

4

Verify fuel pressure

Look for: Compare running/cranking pressure to the vehicle spec. Low or dropping pressure starves multiple cylinders and reads as a random misfire — suspect the pump, filter, or regulator.

5

Compression / leak-down test if ignition and fuel check out

Look for: A cylinder 15%+ below the others, or leak-down hissing from the intake (intake valve), exhaust (exhaust valve), or oil filler (rings), means the misfire is mechanical — not a swap-in part.

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Matching symptoms

Car Runs RoughFlashing Check Engine Light